1. Field of the Invention
The present invention is directed in general to the field of pressure sensor devices. In one aspect, the present invention relates to a micro-electro mechanical system (MEMS) pressure sensor having an improved packaging scheme for producing low cost tire pressure monitoring systems for the automotive industry.
2. Description of the Related Art
Micro-Electro-Mechanical Systems (MEMS) technology is increasingly used to integrate mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. For example, MEMS pressure sensors can be used to automatically measure car tire pressure while the vehicle is moving so that the operators can be notified if the tires are not properly inflated. Improper tire inflation can cause tire damage, increased fuel consumption, reduced vehicle stability and/or vehicle accidents if the tires blow out. By providing real-time air pressure information, the vehicle operator can properly maintain the air pressure of the tires and safely operate the vehicle. However, there are significant technical challenges to placing a pressure sensor in a tire to monitor the air pressure since the environment in the tire where the sensor is placed is quite harsh and corrosive. To protect against the corrosive environment, internal tire pressure sensors are provided with various coatings, encapsulants, or diaphragms made from various elastic gels, polymers, or other materials, but these protection schemes add to the complexity of manufacturing such sensors, resulting in increased cost, reduced reliability, impaired centrifugal performance, and/or reduced ability to measure the air pressure (e.g., due to the presence of a thick coating on the sensing diaphragm).
Accordingly, a need exists for an improved pressure sensor device and manufacture method which overcomes the problems in the art, such as outlined above. Further limitations and disadvantages of conventional processes and technologies will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow.